of;
Remote;
Sensing,;
Nanjing;
University;
of;
Information;
Science;
and;
Technology,;
Nanjing;
210044,;
China;
Laboratory;
of;
Virtual;
Geographic;
Environment,;
Ministry;
of;
Education.;
Nanjing;
Normal;
University,;
Nanjing;
210046,;
China;